Shear reinforcement effect of geosynthetic encased stone column in liquefiable sands

This paper presents a numerical investigation of the shear reinforcement effect of geosynthetic encased stone column (GESC) in liquefiable sands under seismic loading. The sands and stone column were characterized using a pressure-dependent multi-yield surface constitutive model for dynamic analysis. The geosynthetic encasement was represented using linear elastic geogrid element in the finite difference model, which was subsequently validated against shaking table test results for GESC in a saturated loose sand layer, including excess pore water pressure and acceleration time histories. The dynamic response of stone column and GESC unit cell were analyzed and compared. A parametric analysis was subsequently performed to examine the influences of critical design variables such as reinforcement stiffness and surcharge load on the dynamic response of the GESC unit cell. Results demonstrate that the geosynthetic encasement effectively enhances the shear reinforcement effect under seismic loading. Furthermore, the inclusion of geosynthetic encasement effectively improves the stress-strain response of the column and surrounding liquefiable soils. GESC exhibits enhanced shear reinforcement effect under higher vertical stress, increased encasement stiffness, and greater seismic intensity, providing new insights into the shear reinforcement mechanism of GESC, especially the development of longitudinal strain in the encasement under seismic loading.